12-1: Spinal Cord - structure Flashcards
The spinal cord is a cylinder of __NS tissue continuous with the ___.
CNS tissue; medulla of the brainstem
The spinal cord begins at __ and ends __.
foramen magnum; between vertebrae L1 & L2
What are the visible enlargments in the cord?
cervical enlargement - nerves that supply the arms come from this region
lumbar enlargement - nerves that supply the legs come from this region
conus medullaris
tapered end of spinal cord below lumbar enlargement
cauda equina
collection of spinal nerves fanning out from inferior end of cord
What is a bundle of axons in the PNS called?
nerve
What is a bundle of axons in the CNS called?
tract
What are the types of tracts in the CNS?
ascending tract - made of sensory neurons carrying sensory impulses UP the cord to the brain
descending tract - made of motor neurons carrying motor impulses DOWN the cord
What is a cluster of neuron cell bodies in the PNS called?
ganglion
What is a cluster of neuron cell bodies in the CNS called?
nucleus
What grooves divide the spinal cord into right and left halves?
posterior median sulcus and anterior median fissure
A region of grey matter is called __.
horn
Gray matter consists of:
cell bodies, unmyelinated axons and neuroglia; forms an H shaped area in the center of the cord
anterior/ventral horn
cell bodies of outgoing somatic motor neurons
posterior/dorsal horn
cell bodies of incoming sensory neurons and interneurons
lateral horns
cell bodies of autonomic neurons
Sensory signals come from the __ of the cord and motor signals come from the __.
back; front
gray commisure
crossbar of the H - encloses the central canal
central canal
runs the length of the cord and is filled with cerebrospinal fluid; enclosed in the gray commisure
white matter
groups of myelinated axons forming ascending and descending tracts outside the gray matter.
White matter forms areas called:
columns
What are the three columns of white matter?
posterior (dorsal) columns; anterior (ventral) columns; lateral columns
consist of ascending and descending tracts named from their origin and destination (eg. anterior spinothalamic tract - origin is spine and destination is thalamus)
The spinal cord is enclosed in ___ formed by ___.
the spinal canal; formed by the vertebral foramina of the vertebrae stacked on top of each other
cerebrospinal fluid
clear fluid that circulates in the subarachnoid space around the cord and cushions it from shock
meninges
connective tissue covering around the brain and spina l cord
What are the spinal meninges (superficial to deep)?
[bone] >epidural space 1. dura mater 2. arachnoid >subarachnoid space 3. pia mater
dura mater
most superficial meninge; outer layer of dense connective tissue, forms tube around cord called spinal dural sheath
epidural space
between dura mater and bone; filled with fat and blood vessels, and provides soft padding around the cord
arachnoid
fine, spiderweb-like connective tissue between the dura mater and the pia mater
subarachnoid space
between arachnoid and pia mater; where CSF circulates
pia mater
deepest meninge; delicate, transparent membrane on surface of spinal cord
meningitis
an inflammation of the meninges (bacterial or viral)
Anestetics are injected into ___ and lumbar punctures are done ____.
epidural space; subarachnoid space
